Precise bidirectional temperature control method for active hydrogen atomic clock

Abstract

The invention discloses a precise bidirectional temperature control method for an active hydrogen atomic clock, and the method employs a temperature sensor to detect the environment temperature, a microcontroller carries out the temperature control of a case of the hydrogen atomic clock according to a read temperature value fed back by the temperature sensor, and the temperature control of the case of the hydrogen atomic clock is carried out in a TEC temperature control manner. When the temperature of the case of the hydrogen atomic clock reaches a preset temperature range, the microcontroller acquires a temperature value in the case by using a temperature sensor in the case, judges a temperature control mode required by the interior of the cavity according to the acquired temperature value in the case, and controls the interior of the cavity to be heated if the interior of the cavity needs to be heated; if yes, the microcontroller starts a mode of combining a thermistor and a resistance wire to heat the interior of the cavity, if refrigeration is needed in the cavity, a TEC refrigerator attached to the outer wall of the resonant cavity of the hydrogen atomic clock is used for refrigeration, and the temperature in the cavity is reduced in a heat conduction mode; according to the invention, the temperature in the resonant cavity of the hydrogen atomic clock can be kept stable at different external environment temperatures.

Description

Technical Field

[0001] The invention belongs to the field of temperature control, and in particular relates to a precise bidirectional temperature control method for an active hydrogen atomic clock. Background Art

[0002] As a high-precision time and frequency standard, the active hydrogen atomic clock uses atomic storage bubble technology to greatly narrow the resonance spectrum. The accuracy of the hydrogen atomic frequency standard can reach 3×10 -13 , stability can reach 10 -16 / day, but this type of cavity structure has high requirements for the temperature environment. Temperature changes will directly affect the physical properties inside the hydrogen atomic clock, such as the dimensional stability of the resonant cavity. Poor temperature control will cause the stability of the hydrogen atomic clock to deteriorate, directly affecting the long-term stability of the output frequency of the hydrogen atomic clock. Temperature runaway will directly lead to no intermediate frequency signal output by the hydrogen atomic clock. Therefore, in order to ensure that the hydrogen atomic clock can provide accurate and stable frequency signals, it must be precisely temperature controlled.

[0003] In order for a hydrogen atomic clock to have good performance, it is necessary to maintain a high temperature in the cavity. At present, the temperature control of hydrogen atomic clocks is mostly carried out by using thermistors as temperature measuring elements and heating resistors as temperature control elements. Multiple pairs of thermistors and heating resistors are located at different positions in the cavity to maintain the temperature balance in the resonant cavity. The bridge circuit composed of thermistors is used as a temperature sensor in the cavity to read the temperature in the cavity in real time. The output signal of the bridge is processed by analog circuits and PID circuits. The result of signal processing controls the heating wire to heat until the bridge remains balanced, thereby achieving temperature control in the resonant cavity of the hydrogen atomic clock.

[0004] For the temperature control method of hydrogen atomic clock currently used, since only resistance wire is used for temperature control, and the inherent temperature control characteristics of resistance wire can only heat the cavity, but cannot achieve cooling, when the external environment temperature is higher than the optimal temperature required in the hydrogen atomic resonance cavity, it is impossible to effectively control the temperature in the hydrogen atomic resonance cavity, and it is difficult to meet the temperature control requirements of hydrogen atoms under more complex environmental conditions. At the same time, in the hydrogen atomic clock temperature control system with thermistor and heating resistance wire as the core, when the external environment temperature is lower than the optimal temperature required in the cavity, the temperature in the cavity will show a lower temperature characteristic under the unique structure of the cavity, which will lead to the use of excessive power to heat the cavity in the initial stage of temperature control, and the uniform distribution of temperature in the resonance cavity has hysteresis, which will easily lead to control overshoot in the process of resonance cavity temperature control, thereby increasing the time required for hydrogen atomic clock to stabilize, affecting the use of hydrogen atomic clock. Summary of the invention

[0005] In view of this, the present invention provides an active hydrogen atomic clock precision bidirectional temperature control method, which can maintain the temperature stability in the hydrogen atomic clock resonant cavity under different external ambient temperatures, and effectively support the hydrogen atomic clock output signal with good accuracy and stability.

[0006] The technical solution for implementing the present invention is as follows:

[0007] The invention discloses an active hydrogen atomic clock precise bidirectional temperature control method. The temperature sensor is used to detect the ambient temperature. A microcontroller controls the temperature of a hydrogen atomic clock case according to the temperature value fed back by the temperature sensor. The temperature control of the hydrogen atomic clock case is carried out by thermoelectric cooler (TEC) temperature control. When the temperature of the hydrogen atomic clock case reaches a preset temperature range, the microcontroller uses a temperature sensor in the case to obtain the temperature value in the case. The microcontroller determines the temperature control mode required in the cavity according to the obtained temperature value in the case. If heating in the cavity is required, the microcontroller starts heating the cavity by a combination of a thermistor and a resistance wire. If cooling in the cavity is required, the TEC cooler attached to the outer wall of the hydrogen atomic clock resonant cavity is used for cooling, and the temperature in the cavity is reduced by heat conduction.

[0008] Furthermore, a thermistor is used as a temperature sensor inside the chassis to obtain the temperature inside the chassis.

[0009] Furthermore, when the temperature inside the hydrogen atomic clock chassis meets the ±5°C temperature range of the optimal output signal in the cavity, the hydrogen clock chassis temperature control system gives a trigger signal through the microcontroller. The microcontroller processes the data of the ambient temperature in the initial stage and chooses to start different temperature control methods to adjust the temperature in the cavity.

[0010] Furthermore, when the external environment temperature is low and the cavity needs to be heated, the microcontroller starts to heat the cavity by a combination of a thermistor and a resistance wire. Since the thermistor and the thermistor are both placed in the resonant cavity, changes in their heating speed can directly affect whether the temperature in the cavity can be quickly stabilized. The temperature control method of the resistance wire in the cavity adopts fast PID control to achieve rapid temperature adjustment. At the same time, the microcontroller reads the cavity temperature reflected by the resistance value of the thermistor in real time through an analog-to-digital converter, and adjusts the heating voltage loaded on the resistance wire in real time according to the current temperature. The closer the temperature is to the optimal signal output temperature in the cavity, the smaller the heating voltage is, thereby ensuring that there will be no overshoot in the heating process in the cavity, so that the temperature in the cavity can be constant at the fastest speed, thereby improving the stabilization time of the hydrogen atomic clock and the overall performance of the hydrogen atomic clock.

[0011] Furthermore, when the external ambient temperature is high, the microcontroller starts to cool the cavity by combining a thermistor and a ring-shaped TEC cooler; the TEC cooler is made in a ring-shaped manner, and its cold surface is tightly attached to the outer wall of the resonant cavity, and the temperature is conducted to the cavity through the metal thermal conductivity of the outer wall, thereby reducing the temperature in the cavity.

[0012] Beneficial effects:

[0013] 1. The present invention can realize bidirectional precise control of the cavity temperature of the hydrogen atomic clock, so that when there is a large difference between the external ambient temperature and the optimal temperature required in the hydrogen clock cavity, especially when the ambient temperature is higher than the optimal temperature required in the resonant cavity of the hydrogen atomic clock, the temperature control system of the hydrogen atom can still work normally, maintain the internal temperature of the hydrogen clock stable, and improve the environmental adaptability of the hydrogen atom to meet the application of the hydrogen atomic clock in different application scenarios.

[0014] 2. The present invention adjusts the temperature control power in different temperature control modes in real time to avoid the problem of temperature control overshoot under the current mainstream temperature control mode of the hydrogen atomic clock, thereby effectively speeding up the temperature control process and improving the stability and robustness of the hydrogen atom.

[0015] 3. The microcontroller of the present invention controls the refrigeration in the cavity and adopts a slow PID to adjust the annular TEC cooling plate. The temperature in the cavity is fed back by the thermistor in real time. The microcontroller adjusts the current flowing through the annular TEC cooling plate in real time according to the resistance value of the thermistor, thereby limiting the power of the annular TEC refrigerator, thereby adjusting the temperature control in the hydrogen atomic clock cavity to prevent overshoot, and making the temperature control of the hydrogen atomic clock tend to a steady state as soon as possible.

[0016] 4. The microcontroller of the present invention controls the refrigeration in the cavity by using a ring-shaped TEC refrigeration sheet that fits the outer wall of the resonance cavity to adjust the temperature in the cavity by heat conduction, thereby effectively avoiding the temperature of the TEC in the resonance cavity from circulating in the cavity during the refrigeration process, which leads to the inability to effectively control the temperature in the cavity. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The figure is a flow chart of the method of the present invention. DETAILED DESCRIPTION

[0018] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0019] The present invention provides an active hydrogen atomic clock precision bidirectional temperature control method, which aims to adjust and maintain the temperature in the cavity stable when the external environment temperature is lower or higher than the temperature required for the optimal signal output of the hydrogen atomic clock resonant cavity. Figure 1As shown, the method of the present invention mainly consists of three stages, namely, 1. reading the ambient temperature, 2. controlling the temperature of the hydrogen clock case, and 3. controlling the heating temperature in the cavity or the cooling temperature of the cavity wall. The three parts work together to quickly adjust and control the temperature of the hydrogen atom resonance cavity.

[0020] This method uses two-stage temperature control to ensure the temperature inside the hydrogen atomic clock cavity is stable. First, an ambient temperature sensor is installed outside the hydrogen atomic clock chassis to obtain the ambient temperature in the initial state. The microcontroller reads the ambient temperature state through the temperature sensor to adjust the heating and cooling of the temperature control inside the hydrogen atomic clock chassis.

[0021] The temperature control of the hydrogen atomic clock chassis is carried out by TEC temperature control. Thermistors are used as temperature sensors in the chassis to obtain the temperature in the chassis. The microcontroller controls the TEC cooler through a slow PID control algorithm according to the ambient temperature state and thermistor value state in the chassis to achieve chassis temperature regulation. At the same time, in the process of controlling the chassis temperature, the microcontroller processes the ambient temperature data and synchronously adjusts the TEC drive current to limit the temperature control power of the TEC cooler, thereby ensuring that the temperature control of the chassis can enter a steady state in a relatively short time (the optimal output signal temperature requirement range in the hydrogen atomic clock cavity is ±5°C), and maintain the long-term temperature stability of the chassis in the hydrogen atomic clock.

[0022] When the temperature inside the hydrogen atomic clock chassis is within ±5°C of the optimal output signal temperature range in the cavity (for example, the optimal output signal temperature range is a~b, and the microcontroller sends a trigger signal when the temperature inside the chassis is a-5~b+5), the hydrogen clock chassis temperature control system gives a trigger signal through the microcontroller. The microcontroller processes the data of the ambient temperature in the initial stage and chooses to start different temperature control methods to adjust the temperature in the cavity. When the external environment temperature is low, the cavity needs to be heated. The microcontroller starts to heat the cavity by combining thermistors and resistance wires. Since thermistors and thermistors are placed in the resonant cavity, changes in their heating speed can directly affect whether the temperature in the cavity can be quickly stabilized. The temperature control method of the resistance wire in the cavity adopts fast PID control to achieve rapid temperature adjustment. At the same time, the microcontroller reads the cavity temperature reflected by the resistance value of the thermistor in real time through an analog-to-digital converter, and adjusts the heating voltage loaded on the resistance wire in real time according to the current temperature. The closer the temperature is to the optimal signal output temperature in the cavity, the smaller the heating voltage is, thereby ensuring that there will be no overshoot in the heating process in the cavity, so that the cavity can complete the temperature constant at the fastest speed, improve the stabilization time of the hydrogen atomic clock, and improve the overall performance of the hydrogen atomic clock.

[0023] When the ambient temperature is high, the microcontroller starts to cool the cavity by combining thermistors and annular TEC coolers. Due to the inherent characteristics of the TEC cooler, its heating and cooling are on opposite sides. If the TEC cooler is directly installed in the resonant cavity, the thermal cycle of the TEC will be mainly carried out in the cavity, and the temperature in the cavity cannot be effectively regulated. At the same time, in order not to affect the inherent structure of the cavity and maintain the miniaturization of the resonant cavity, the TEC cooler is made in a ring-shaped manner, and its cold surface is tightly attached to the outer wall of the resonant cavity. The temperature is conducted to the cavity through the metal thermal conductivity of the outer wall, thereby reducing the temperature in the cavity. Since heat conduction is a slow process, the microcontroller uses a slow PID to adjust the annular TEC cooler for the cooling control in the cavity. The thermistor feeds back the cavity temperature in real time. The microcontroller adjusts the current flowing through the annular TEC cooler in real time according to the resistance value of the thermistor, thereby limiting the power of the annular TEC cooler, thereby adjusting the temperature control in the hydrogen atomic clock cavity to prevent overshoot, and making the temperature control of the hydrogen atomic clock tend to steady state as soon as possible.

[0024] In summary, the above are only preferred embodiments of the present invention and are not intended to limit the protection scope of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A precise bidirectional temperature control method for an active hydrogen atomic clock, characterized in that: First, the ambient temperature is detected by a temperature sensor, and the microcontroller controls the temperature of the hydrogen atomic clock chassis according to the temperature value fed back by the temperature sensor. The temperature control of the hydrogen atomic clock chassis is carried out by TEC temperature control. When the temperature of the hydrogen atomic clock chassis reaches a preset temperature range, the microcontroller uses the temperature sensor inside the chassis to obtain the temperature value inside the chassis. The microcontroller determines the required temperature control method in the cavity according to the obtained temperature value inside the chassis. If heating of the cavity is required, the microcontroller starts heating the cavity by a combination of a thermistor and a resistance wire. If cooling of the cavity is required, the TEC cooler attached to the outer wall of the hydrogen atomic clock resonant cavity is used for cooling, and the temperature in the cavity is reduced by heat conduction.

2. The active hydrogen atomic clock precision bidirectional temperature control method as claimed in claim 1, characterized in that: A thermistor is used as a temperature sensor inside the chassis to obtain the temperature inside the chassis.

3. The active hydrogen atomic clock precision bidirectional temperature control method as claimed in claim 1, characterized in that: When the temperature inside the hydrogen atomic clock chassis meets the optimal output signal temperature range of ±5°C in the cavity, the hydrogen clock chassis temperature control system gives a trigger signal through the microcontroller. The microcontroller processes the data of the ambient temperature in the initial stage and chooses to start different temperature control methods to adjust the temperature in the cavity.

4. The active hydrogen atomic clock precision bidirectional temperature control method according to claim 1 or 3, characterized in that: When the external environment temperature is low, the cavity needs to be heated. The microcontroller starts to heat the cavity by combining thermistors and resistance wires. Since both thermistors and thermistors are placed in the resonant cavity, changes in their heating speed can directly affect whether the temperature in the cavity can be quickly stabilized. The temperature control method of the resistance wire in the cavity adopts fast PID control to achieve rapid temperature adjustment. At the same time, the microcontroller reads the cavity temperature reflected by the resistance value of the thermistor in real time through an analog-to-digital converter, and adjusts the heating voltage loaded on the resistance wire in real time according to the current temperature. The closer the temperature is to the optimal signal output temperature in the cavity, the smaller the heating voltage is, thereby ensuring that there will be no overshoot in the heating process in the cavity, so that the cavity can complete temperature stability at the fastest speed, improve the stabilization time of the hydrogen atomic clock, and improve the overall performance of the hydrogen atomic clock.

5. The active hydrogen atomic clock precision bidirectional temperature control method according to claim 1 or 3, characterized in that: When the external ambient temperature is high, the microcontroller starts to cool the cavity by combining a thermistor and a ring-shaped TEC cooler. The TEC cooler is made in a ring shape, and its cold surface fits tightly against the outer wall of the resonant cavity. The temperature is conducted to the cavity through the metal thermal conductivity of the outer wall, thereby reducing the temperature inside the cavity.

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